Production of oil and gas (e.g., hydrocarbons) from subterranean formations is dependent on many factors. These hydrocarbons must usually migrate through a low permeable formation matrix to drain into the wellbore. In many formations, the permeability is so low that it hinders the well's production rate and overall potential. In other wells, the near wellbore is damaged during drilling operations and such damage often results in less than desirable well productivity. Hydraulic fracturing is a process designed to enhance the productivity of oil and gas wells or to improve the infectivity of injection wells.
In the fracturing process, a viscous fluid is injected into the wellbore at such a rate and pressure as to induce a crack or fracture in the formation. Once the fracture is initiated, a propping agent, such as sand (e.g., often referred to as “frac” sand), is added to the fluid just prior to entering the wellbore. This sand laden slurry is continuously injected causing the fracture to propagate or extend. After the desired amount of proppant has been placed in the reservoir, pumping is terminated, and the well is shut-in for some period of time.
After the pressure is released from the wellbore, the sand, or at least a significant portion of the sand, remains within the fractured strata thereby holding the strata in a substantially fractured state. Accordingly, the oil and gas is allowed to flow freely. Unfortunately, as the oil and gas begin to flow it starts to push the fluid used to fracture the strata, as well as some unwanted particulates from the strata (including, frac sand, salts, etc.) back to the surface.
Simple frac tanks are commonly used to collect the unwanted fluid and particulates that backflow from the wellbore. A typical frac tank is configured as a large enclosure having a valve at the bottom thereof, often using a “gas buster” to dissipate the velocity of the backflow. When the frac tank is full of collected fluid, sand, salts, hydrocarbons, etc., an environmentally approved service must be employed to remove the contents thereof. A typical removal process initiates by removing the fluid from the frac tank via the valve at the bottom thereof. In this situation, as the sand is heavier than the other particles, the sand would be at the bottom of the tank. The fluid, hydrocarbons, salts, etc., most of which would be suspended in the fluid, would then be drawn through the sand and collected and disposed of. Unfortunately, the sand, in this removal scenario, becomes contaminated as the hydrocarbons and salts are drawn there through. Therefore, the sand must then be removed from the frac tank and processed so as to be safe for the environment. This process of collecting, removing, and decontaminating the backflow, including both the fluid and sand, is an extremely expensive process.
Accordingly, what is needed in the art is apparatus, and/or associated process, which reduces the time and expense associated with the collection and dispersal of the backflowed contaminants.